frontal gyrus any of the three (inferior, middle, and superior) gyri of the frontal lobe.

fusiform gyrus one on the inferior surface of the hemisphere between the inferior temporal and parahippocampal gyri, consisting of a lateral (lateral occipitotemporal gyrus) and a medial (medial occipitotemporal gyrus) part.

hippocampal gyrus (gyrus hippocam´pi) one on the inferior surface of each cerebral hemisphere, lying between the hippocampal and collateral fissures; called also parahippocampal gyrus.

infracalcarine gyrus (lingual gyrus) one on the occipital lobe that forms the inferior lip of the calcerine sulcus and, together with the cuneus, the visual cortex.

marginal gyrus the middle frontal gyrus.

occipital gyrus any of the three (superior, middle, and inferior) gyri of the occipital lobe.

occipitotemporal gyrus, lateral the lateral portion of the fusiform gyrus.

occipitotemporal gyrus, medial the medial portion of the fusiform gyrus.

orbital gyri irregular gyri on the orbital surface of the frontal lobe.

paraterminal gyrus a thin sheet of gray matter in front of and ventral to the genu of the corpus callosum.

postcentral gyrus the convolution of the frontal lobe immediately behind the central sulcus; the primary sensory area of the cerebral cortex; called also posterior central gyrus.

precentral gyrus the convolution of the frontal lobe immediately in front of the central sulcus; the primary motor area of the cerebral cortex; called also anterior central gyrus.

gyrus rec´tus a cerebral convolution on the orbital aspect of the frontal lobe.

supramarginal gyrus that part of the inferior parietal convolution which curves around the upper end of the fissure of Sylvius.

temporal gyrus any of the gyri of the temporal lobe, including inferior, middle, superior, and transverse temporal gyri; the more prominent of the latter (anterior transverse temporal gyrus) represents the cortical center for hearing.

gy·rus

, gen. and pl.

gy·'ri

(jī'rŭs, -rī), [TA]

One of the prominent rounded elevations or convolutions that form the cerebral hemispheres, each consisting of an exposed superficial portion and a portion hidden from view in the wall and floor of the sulcus (q.v.).

interlocking gyri small gyri in the opposing walls of the central sulcus that interlock with each other like gears.

lingual gyrus one on the occipital lobe, forming the inferior lip of the calcarine sulcus and, with the cuneus, the visual cortex.

gyrus lon´gus in´sulae the long, occipitally directed gyrus on the surface of the insula.

occipital gyrus either of the two (superior and inferior) gyri of the occipital lobe.

occipitotemporal gyrus, lateral the lateral portion of the fusiform gyrus.

occipitotemporal gyrus, medial the medial portion of the fusiform gyrus.

orbital gyri irregular gyri on the orbital surface of the frontal lobe.

parahippocampal gyrus a convolution on the inferior surface of each cerebral hemisphere, lying between the hippocampal and collateral sulci.

paraterminal gyrus a thin sheet of gray substance in front of and ventral to the genu of the corpus callosum.

postcentral gyrus the convolution of the frontal lobe between the postcentral and central sulci; the primary sensory area of the cerebral cortex.

precentral gyrus the convolution of the frontal lobe between the precentral and central sulci; the primary motor area of the cerebral cortex.

gyrus rec´tus one on the orbital surface of the frontal lobe.

supramarginal gyrus that part of the inferior parietal convolution that curves around the upper end of the sylvian fissure.

temporal gyrus any of the gyri of the temporal lobe, including the inferior, middle, superior, and transverse temporal gyri; the more prominent of the latter (anterior transverse temporal g.), when two exist, represents the cortical center for hearing.

gy´ri transiti´vi ce´rebri various small folds on the cerebral surface that are too inconstant to bear individual names.

gyrus

(jī′rəs)

n.pl.gy·ri(-rī′)

A rounded ridge, as on the surfaces of the cerebral hemispheres.

gyrus

[jī′rəs][jī′rī]pl. gyri

Etymology: Gk, gyro, circle

one of the winding convolutions of the cerebral hemisphere of the brain. They are caused by infolding of the cortex and are separated by the shallow grooves (sulci) or deeper grooves (fissures). See also cerebral cortex.

gy·rus

, pl. gyri (jī'rŭs, -rī) [TA]

One of the prominent rounded elevations or convolutions that form the cerebral hemispheres, each consisting of an exposed superficial portion and a portion hidden from view in the wall and floor of the sulcus.

[L. fr. G. gyros, circle]

gyrus

(ji'rus) plural.gyri [L. gyrus fr. Gr. gyros, ring, circle]

CEREBRAL GYRI

Any of the surface convolutions or rounded ridges that are packed along the cerebral hemispheres of the brain. Each gyrus is separated from its neighbor by a furrow called a sulcus. Details of the shape of gyri vary from individual to individual. Synonym: convolution; gyre See: illustration

angular gyrus

A gyrus of the ventral region of the parietal lobe; it caps the posterior (ascending) end of the superior temporal sulcus, and it is just ventral to the supramarginal gyrus. The cortex of the angular gyrus plays a role in the association of the visual and tactile perceptions of forms and shapes.

gyrus angularis

Broca gyrus

callosal gyrus

A large gyrus on the medial surface of the cerebral hemisphere that lies directly above the corpus callosum and arches over its anterior end.

gyrus cerebelli

A layer of the cerebellum.

cingulate gyrus

A long curving gyrus on the medial surface of each cerebral hemisphere; it follows the arch of the corpus callosum, from which it is separated by a deep fissure, the callosal sulcus. The cortex of the cingulate gyrus and the underlying axon tract, the cingulum, are parts of the main circuitry of the limbic system.

dentate gyrus

A curved gyrus hidden along the medial surface of the temporal lobe of each cerebral hemisphere. It contains a cortex of three layers, with a single cell layer, that is part of the hippocampal formation, and it is folded inside the hippocampal sulcus, where it lies against the subicular edge of the parahippocampal gyrus. The surface of the dentate gyrus has regularly-spaced transverse grooves, which make the gyrus resemble a row of teeth.

gyrus fornicatus

The ring along the medial surface of each cerebral hemisphere that forms a large segment of the limbic circuitry. The gyrus fornicatus comprises the subcallosal gyrus, the cingulate gyrus, the retrosplenial area, the parahippocampal gyrus, and the uncus.

fusiform gyrus

Occipitotemporal gyrus.

Heschl gyrus

hippocampal gyrus

inferior frontal gyrus

The inferior-most of the three major longitudinal gyri of the lateral surface of the frontal lobe of each cerebral hemisphere; it is part of the prefrontal cortex. In the dominant hemisphere, the posterior two-thirds of the inferior frontal gyrus are Broca speech area, which is involved in activating the muscle groups used when speaking

inferior occipital gyrus

A stubby, knuckle-shaped gyrus on the lateral surface of the occipital lobe of each cerebral hemisphere, just below the lateral occipital sulcus.

inferior parietal gyrus

inferior temporal gyrus

The inferior-most of the three longitudinal gyri that cover the lateral surface of the temporal lobe.

lingual gyrus

A tongue-shaped gyrus that, at its anterior end (tip), abuts the parahippocampal gyrus on the under surface (ventral) of the occipital lobe. The calcarine fissure (calcarine sulcus) forms the medial (upper) edge of the lingual gyrus, and the collateral sulcus forms the lateral (lower) edge. Part of the primary visual cortex is found along the wall of the lingual gyrus inside the calcarine fissure.

gyrus longus insulae

A lengthy gyrus composing the postinsula.

medial frontal gyrus

The major anterior gyrus of the medial surface of the frontal lobe of each cerebral hemisphere; it is part of the prefrontal cortex. The medial frontal gyrus curves over the cingulate gyrus, separated from it by the cingulate sulcus.

middle frontal gyrus

The middle of the three major longitudinal gyri of the lateral surface of the frontal lobe of each cerebral hemisphere; it is part of the prefrontal cortex.

middle temporal gyrus

The middle the three longitudinal gyri that cover the lateral surface of the temporal lobe.

occipital gyrus

The inferior or the superior occipital gyrus.

occipitotemporal gyrus

The lateral or the medial occipitotemporal gyrus, both of which run longitudinally along the bottom (ventral surface) of the temporal lobe of each cerebral hemisphere.

orbital gyrus

Any of the gyri forming the inferior, concave surface of the frontal lobe, which lies along the orbital surface of the frontal bone.

paracentral gyrus

parahippocampal gyrus

A gyrus along the medial (inner) edge of the temporal lobe of each cerebral hemisphere; it is bounded by the hippocampal fissure medially and the collateral sulcus laterally. The medial edge of the parahippocampal gyrus is called the subiculum; the remainder of the gyrus is called the entorhinal cortex. Together, the ventricular side of the subiculum and dentate gyrus form the hippocampus.

paraterminal gyrus

A small area of the cerebral cortex anterior to the lamina terminalis and below the rostrum of the corpus callosum.

parietal gyrus

The inferior or the superior parietal lobule.

postcentral gyrus

A major dorsoventral gyrus in the parietal lobe of each cerebral hemisphere; its anterior border is the central sulcus, and its posterior border is the postcentral sulcus. This gyrus contains the primary somatosensory cortex. Synonym: ascending parietal convolution

posterior central gyrus

precentral gyrus

A major dorsoventral gyrus in the parietal lobe of each cerebral hemisphere; its anterior border is the precentral sulcus, and its posterior border is the central sulcus. This gyrus contains the primary motor cortex. Synonym: ascending frontal convolution

gyrus profundus cerebri

One of the very deep gyri of the cerebrum.

gyrus rectus

A longitudinal gyrus on the medial edge of the orbital (ventral) surface of the frontal lobe of each cerebral hemisphere; the lateral edge of the gyrus rectus is the olfactory sulcus.

Retzius gyrus

subcallosal gyrus

The short gyrus at the head of the cingulate gyrus, just below the rostrum of the corpus callosum, on the medial surface of each cerebral hemisphere. It is the anterior-most segment of the gyrus fornicatus.

superior parietal gyrus

superior temporal gyrus

supracallosal gyrus

supracallosus gyrus

The gray matter layer covering the corpus callosum.

supramarginal gyrus

A V-shaped gyrus capping the posterior end of the Sylvian fissure in the parietal lobe of each cerebral hemisphere, just dorsal to the angular gyrus. The supramarginal gyrus plays a role in auditory comprehension.

temporal gyrus

transverse temporal gyrus

uncinate gyrus

gyrus

One of the many lobe-like rounded elevations on the surface of the brain resulting from the infolding of the adjacent grooves (sulci). From the Greek guros , a circle.

gyrus

prominent, rounded, folded elevation within the cerebral hemispheres

gyrus

One of the prominent rounded elevations between the sulci or grooves on the surface of the hemispheres of the brain. There are numerous gyri. Those associated with the visual association areas are the angular and lingual gyri. Plural: gyri.

gy·rus

, pl. gyri (jī'rŭs, -rī) [TA]

One of the prominent rounded elevations or convolutions that form the cerebral hemispheres, each consisting of an exposed superficial portion and a portion hidden from view in the wall and floor of the sulcus (q.v.).

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